Soundhole covers - grr...

All soundhole covers seem to be standard 4" or 100mm, but the soundhole on my guitar is more like 97mm. The manufacturer's website suggests the "Feedback buster" and I had the impression this was slightly smaller, but I just unwrapped one and, nope - 100mm, no way that'll fit.

I've found plenty of forum posts where people are rambling about this problem, and different soundhole types and sizes, but what are you supposed to do...? Seems ridiculous. The most popular answer seems to be lutehole.com. They look great, and made to measure, but not cheap. Looking at the design it seems you don't need to completely block the hole to prevent feedback, so why isn't there a simple, cheap, one-size-fits-all adjustable type? If it exists, I can't find it.

Also, am I definitely going to need one of these? I'm surprised at a guitarist I know who regularly plays live gigs but seems strongly opposed to using one on the basis that it spoils the tone.

Do you HAVE a feedback problem? They are by no means standard equipment. In fact, I'm not a guitarist, but I'd never even heard of such things! Are they for acoustic guitarists who play on stages with over-loud monitoring levels?

They do affect the tone - sometimes to damp the lovely resonant low mids, other times to kill the uncontrollable feedback that makes playing impossible.

I have feedback busters anywhere I can fit them. Where I can't get a commercially available one I've made my own. If you can get your hands on a rubber backed "bar towel" from a helpful landlord you can make something useful by cutting two circles slightly larger than your soundhole, glue one on top of the other (pic side in) with a circle of cardboard box slightly smaller than the soundhole between the two.

Voila!

P.S.
Off cuts of "wood effect" vinyl flooring are also a winner. Sales folks are often happy to provide a piece so you can show the wife. It would obviously need to be a useful size so she can appreciate the pattern properly - and it's a big room - and you'll need them to deliver and fit it.

I bought a dedicated acoustic for one band I was in, we played country rock and were fairly loud. I fitted it with a modified feedback buster around my preferred Fishman Rare Earth pickup and, more importantly, it had wooden blocks inside wedged between the bridge plate and back to kill the resonance of the top. It worked well enough that I could play an acoustic without issues on a loud stage. Fully reversible too but it totally killed the acoustic tone as you would imagine until I eventually removed it all to sell the guitar when the band broke up.

As Wombat says, they are not standard issue and unless you are playing at rock band levels your guitar will sound better without.

It's a 1st post, so the mods must have let it through. It is appropriate to the (old) topic in question, and no-one else has posted a link to that company, so I expect that one post has been allowed, or no-one would be the wiser.

In the UK the reflective markers in between the white lines are called "Cats eyes", because they uses to be two glass spheres with reflective backing. They looked like cats eyes.The old joke is that the man who invented them had the idea when he saw a cat walking towards him. And the man who watched the same cat walking away from him had the idea for the pencil sharpener...

Nearly right (pedant alert) they didn't have, or need, a reflective backing the glass spheres were sufficient on their own.

More interestingly, they were designed to be self cleaning, every time a car ran over them the rubber housing compressed into the cast iron base wiping the glass sphere clean in the process. Genius.......